PAGE 17323 REV.030624
FAILURE
PROBABLE CAUSE
a) Brake plates or divider plates have been damaged by
contamination in the hydraulic fluid, or lack of circulation
flow in the brake housing.
b) Brake piston is seized in the brake housing because of
contamination in the hydraulic fluid.
c) Excessive back pressure in the return line causes the
brake to be released.
d) Control valve has incorrect spool, which traps hydraulic
pressure in the brake piston when the control valve handle
is returned to neutral position. For proper function of the
automatic brake, both pressure ports of the winch must be
open to the reservoir in neutral position of the control valve.
e) Hydraulic pressure is trapped in the clutch piston,
preventing total engagement. This is caused by using an
incorrect control valve. The free fall control valve must
leave the free fall release port open to reservoir when not
activated.
f) Wire rope is fastened to the incorrect cable anchor slot.
g) Sprag clutch is damaged or surfaces where sprag clutch
engages on motor drive shaft or brake hub are worn or
indented.
h) Winch supplied with external brake release option is not
plumbed per TYPICAL HYDRAULIC CIRCUIT. Failure
to vent external brake release port to reservoir may trap
pressure and cause winch brake to slip.
a) Pump does not supply sufficient flow. Pump rpm must be
maintained at normal operating speed when a load is
lowered.
b) Brake is running too hot. This is caused by insufficient
circulation flow. To check the circulation, observe the flow
of oil from the circulation return line of the winch (approx.
5 (US) gpm - 19 l/min when the winch is reversed).
c) Control valve for the winch operation has poor ‘metering’
characteristics.
d) Damaged brake plates or divider plates.
e) The over-running clutch, which connects the motor shaft
with the brake assembly, is damaged.
f) Air mixed with hydraulic oil (foamy oil).
a) Insufficient pressure or flow supplied to free fall release
port (refer to TYPICAL HYDRAULIC CIRCUIT).
b) O-ring seals in clutch piston are damaged.
c) Insufficient load on the wire rope. A minimum of 1000 lb
(454 kg) on a standard -1 drum is required to drop a load
in free fall.
Brake will not hold.
Brake vibrates when powering down a load.
Free fall clutch cannot be disengaged.
Refer to the SERVICE INSTRUCTIONS if it becomes necessary to disassemble the Model M50 free fall winch.
TROUBLESHOOTING CONTINUED
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